High Surf Advisory 39, NWS Guam

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
740 AM CHST MON OCT 5 2015

.SYNOPSIS...
PGUA DOPPLER WEATHER RADAR SHOWS ALMOST NO SHOWERS WITHIN THE
MARIANAS WATERS. THE VAD WIND PROFILE REVEALS NORTHWEST WINDS OF
15 TO 23 KNOTS THROUGH THE LOWEST 7 THOUSAND FEET OF THE AIR.

&&

.DISCUSSION...
NORTHWEST WINDS TO THE SOUTHWEST OF TROPICAL STORM CHOI-WAN WILL
GRADUALLY SHIFT TOWARD THE WEST. THIS PATTERN WILL DOMINATE
WEATHER OVER THE MARIANAS THROUGH THE NEXT FEW DAYS. WINDS AND
SWELLS WILL BE THE PRIMARY EFFECTS. THE MONSOON TAIL WILL GIVE US
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS BETWEEN TUESDAY
NIGHT AND WEDNESDAY NIGHT. AFTER THAT...WINDS...SWELL AND SHOWERS
WILL TEND TO DIMINISH.

&&

.MARINE...
RITIDIAN AND IPAN BUOYS READ AROUND 6 FEET. FORECASTED 6 TO 8 FEET
SINCE WE EXPECT THEM TO INCREASE A BIT. THE TANAPAG BUOY SHOWED 10
FEET...SO WITH WINDS ALSO EXPECTED TO INCREASE THERE...ISSUED A
SMALL CRAFT ADVISORY THROUGH 6 AM THURSDAY. THE ADVISORY WILL
PROBABLY NEED TO BE EXTENDED TO THE GUAM AND ROTA WATERS LATER
TODAY. DID NOT DO THAT AT THIS TIME THOUGH.

&&

.TROPICAL SYSTEMS...
TROPICAL STORM CHOI-WAN IS MOVING WEST-NORTHWEST EAST OF THE FAR
NORTHERN MARIANAS. IT IS EXPECTED TO TURN NORTHWEST AND PASS WELL
NORTHEAST OF THE FORECAST ZONES. THE REMAINS OF TROPICAL
DEPRESSION 08C WILL MOVE ACROSS THE DATE LINE IN THE NEXT COUPLE
DAYS. IT MAY REGENERATE. TROPICAL STORM 07C OHO IS EXPECTED TO
MOVE NORTHEASTWARD...PASSING EAST OF THE HAWAIIAN ISLANDS.

&&

.EASTERN MICRONESIA...
FRESH TO STRONG MONSOON FLOW WILL PERSIST THE NEXT COUPLE DAYS AT
POHNPEI AND CHUUK. WINDS ARE DECREASING AT KOSRAE AND MAJURO AS A
RIDGE BUILDS IN THERE FROM THE SOUTH. THE MONSOON TROUGH IS LOCATED
WELL NORTH OF THE AREA STRETCHING SOUTHEASTWARD FROM THE LARGE
TROPICAL STORM CHOI-WAN NEAR 22N155E THROUGH THE DATELINE TO THE
REMNANTS OF TROPICAL DEPRESSION 08C CENTERED NEAR 11N172W. MAINLY
ISOLATED SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS ARE EXPECTED
ACROSS MUCH OF THE REGION TODAY...WITH DRIER WEATHER EXPECTED
THROUGH MIDWEEK AT LOCATIONS WEST OF MAJURO. CONVERGENT FLOW
ACROSS THE MARSHALL ISLANDS WILL MAINTAIN SHOWERY CONDITIONS AT
MAJURO.

IN THE LONG-TERM...08C IS EXPECTED TO STRENGTHEN AS IT HEADS
ACROSS THE DATELINE NORTH OF MAJURO BY THE END OF THE WEEK. THE
MONSOON FLOW WILL AGAIN SURGE ACROSS THE REGION WITH WEST WINDS
INCREASING AT MAJURO BY WEDNESDAY...AND KOSRAE BY THURSDAY.
SIMILARLY...SHOWERY CONDITIONS WILL DEVELOP AT THESE LOCATIONS
THEN.

PERSISTENT MONSOONAL WEST SWELL AND WIND WAVES...AND LONG-PERIOD
NORTH SWELL GENERATED BY THE LARGE WIND FIELD OF TROPICAL STORM CHOI-
WAN WILL MAINTAIN HAZARDOUS SEAS AND SURF ACROSS CHUUK AND POHNPEI
STATES THRU MONDAY EVENING. ONCE THE STRONG MONSOON WINDS HAVE
SHIFTED NORTHWEST OF POHNPEI ON TUESDAY... BOTH SEAS AND SURF SHOULD
START TO SUBSIDE. IT WILL TAKE LONGER FOR THEM TO SUBSIDE ON CHUUK
AS STRONG MONSOON WINDS WILL LAST THROUGH TUESDAY.

SEAS AND SURF WILL BUILD AT MAJURO TOWARDS THE END OF THE WEEK AS TD
08C DEVELOPS AND HEADS NORTH OF MAJURO. WILL WATCH THIS CLOSELY AS
THIS SYSTEM EVOLVES OVER THE NEXT FEW DAYS.

&&

.WESTERN MICRONESIA...
REASONING FOR THE CHUUK FORECAST IS INCLUDED IN THE EASTERN
MICRONESIA DISCUSSION DUE TO A SIMILAR MONSOON PATTERN.

CURRENT IR SATELLITE SHOWS ONLY A FEW CLOUDS OVER YAP STATE AND THE
REPUBLIC OF PALAU THIS MORNING. A FEW THUNDERSTORMS ARE SEEN TO THE
EAST AND WEST OF KOROR. THE MONSOON TROUGH IS POSITIONED JUST NORTH
OF YAP...HEADING EAST-NORTHEAST INTO TROPICAL STORM CHOI-WAN...
LOCATED WELL NORTHEAST NEAR 22N155E. LATEST MODEL RUNS SHOW A
DRIER BIAS FOR THE NEXT FEW DAYS AS COMPARED TO MODEL RUNS
YESTERDAY. HOWEVER...MONSOON FLOW IS EXPECTED TO STRENGTHEN THE
NEXT COUPLE OF DAYS THROUGH MIDWEEK AS CHOI-WAN CONTINUES WEST-
NORTHWEST. WINDS WILL DECREASE IN RESPONSE TO A WEAKER MONSOON
TROUGH LATER IN THE WEEK...BUT MODELS SHOW THE MONSOON FLOW
STRENGTHENING IN THE LONG-TERM IN RESPONSE TO ANOTHER DISTURBANCE
IN EASTERN MICRONESIA OVER THE WEEKEND.

LONG-PERIOD NORTH-NORTHEAST SWELL PRODUCED BY THE LARGE WIND FIELD
OF CHOI-WAN WILL REACH THE REPUBLIC OF PALAU AND YAP STATE LATE
TONIGHT AND CONTINUE TO BUILD THE NEXT COUPLE DAYS. IN CONJUNCTION
WITH INCREASING MONSOONAL SWELL AND WIND WAVES...BOTH SEAS AND SURF
WILL APPROACH HAZARDOUS LEVELS BY MIDWEEK.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...NONE.
MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 6 AM CHST THURSDAY
                  FOR PMZ153-154.

&&

STANKO/M. AYDLETT